From my wanderings around the web, Wilderness Logics is about the cheapest you'll get. They sell by the ounce and will bag it up in half ounce and ounce baggies. All for $7 an ounce.
Most other venders are running about $10 an ounce, in 3oz increments, and $13 an ounce if you want it packaged by the ounce.
"In the beginning, all America was Virginia." -William Byrd